Idiopathic Inflammatory Myopathies Subtypes Research Articles

Polymyositis and dermatomyositis – challenges in diagnosis and management

Polymyositis (PM) and dermatomyositis (DM) are different disease subtypes of idiopathic inflammatory myopathies (IIMs). The main clinical features of PM and DM include progressive symmetric, predominantly proximal muscle weakness. Laboratory findings include elevated creatine kinase (CK), autoantibodies in serum, and inflammatory infiltrates in muscle biopsy. Dermatomyositis can also involve a characteristic skin rash. Both polymyositis and dermatomyositis can present with extramuscular involvement. The causative factor is agnogenic activation of immune system, leading to immunologic attacks on muscle fibers and endomysial capillaries. The treatment of choice is immunosuppression. PM and DM can be distinguished from other IIMs and myopathies by thorough history, physical examinations and laboratory evaluation and adherence to specific and up-to-date diagnosis criteria and classification standards. Treatment is based on correct diagnosis of these conditions.

Radiographic patterns of muscle involvement in the idiopathic inflammatory myopathies.

This study assesses the burden, distribution, and evolution of muscle inflammation and damage on MRI among subtypes of idiopathic inflammatory myopathy (IIM). Musculoskeletal MRIs performed in 66 patients with IIM and 10 patients with non-IIM between 2009 and 2016 were retrospectively graded for muscle edema, fatty replacement (FR), and atrophy. Immune-mediated necrotizing myopathy (IMNM) patients had severe and extensive lower limb muscle edema, FR, and atrophy. The pelvic muscles and adductors were significantly more affected than in patients with dermatomyositis and polymyositis. Inclusion body myositis (IBM) was characterized by marked anterior thigh involvement, which stabilized or progressed at follow-up imaging. Atrophy and FR grades improved over time in some non-IBM IIM patients. Patients with IMNM and IBM have characteristic patterns of muscle MRI abnormalities that may allow them to be differentiated radiologically from other IIM subtypes. Muscle damage in non-IBM IIM may be reversible.

Pitfalls in the detection of myositis specific antibodies by lineblot in clinically suspected idiopathic inflammatory myopathy

Today, the contribution of myositis-specific autoantibodies (MSA) in the diagnostic workup of idiopathic inflammatory myopathies (IIM) is on the rise. The aim of this study was to document MSA frequency as detected by lineblot in a set of consecutive MSA requests and to correlate the results with clinical diagnosis, IIM subtype and indirect immunofluorescence (IIF) findings. Additionally, a comparison between two lineblots was performed. A total of 118 consecutive samples of patients with suspicion of IIM were analysed on IIF and two lineblots. A total of 107 patients with autoimmune rheumatic diseases served as controls. MSA were detected in 55% of IIM patients (n=31) and 7.9% (n=12) of patients without clinical diagnosis of IIM or myositis overlap syndrome. All the IIM patients had a MSA-compatible clinical subtype. There was no to fair agreement between both lineblots for the individual antibodies, with most discrepancies observed for anti-TIF1γ (κ=-0.021), anti-SRP (κ=-0.006) and anti-SAE (κ=0.395). Differences between both assays were mostly observed in the non-IIM patients, also showing signi cantly lower blot signal intensities compared to IIM patients (p=0.0013). MSA in the non-IIM patients frequently showed an incompatible IIF pattern. Lineblot seems to be an interesting tool for MSA detection in a clinical context, allowing the identification of clinical subtypes. However, considerable caution must be exercised in interpreting the results in case of low positive MSA signal intensity, discordant lineblot results and/or an incompatible IIF pattern.

Disability in idiopathic inflammatory myopathies: questionnaire-based study

Idiopathic inflammatory myopathies (IIM) are progressive, debilitating diseases that can lead to severe impairment. The aim of the study was to evaluate the level of disability and compare it between different subtypes of IIM as well as to estimate clinical symptoms associated with greater risk of disability and distinguish the most troublesome activities in this group of patients. A online form concerning clinical symptoms, comorbidities and limitations in daily living was created and distributed to online support groups for patients with IIM. Health Assessment Questionnaire was used to estimate disability and physical limitations while visual analogue scales enabled to assess the intensity of clinical symptoms. 361 out of 377 responders were included for further evaluation. High prevalence of disability was observed in each subtype yet predominantly in patients with inclusion body myositis (IBM) as 51.43% of them fulfilled the criteria of severe to very severe disability. Level of disability correlated with muscle weakness, tolerance of physical activity and level of fatigue. 45.62% of responders in general required walking devices and 43.50% of participants declared using facilitating devices for maintaining hygiene. Patients with IIM encounter multitude physical limitations that can be partially compensated by usage of facilitating devices or aid of the caregivers. IBM seems to be the most disabling subtype.

The performance of the European League Against Rheumatism/American College of Rheumatology idiopathic inflammatory myopathies classification criteria in an expert-defined 10 year incident cohort.

ObjectivesTo assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria in a cohort of incident IIM cases and examine how criteria-assigned IIM subtype correlates with expert opinion.MethodsAdults with newly diagnosed IIM attending Salford Royal NHS Foundation Trust were identified over a 10 year period. A retrospective review of all putative cases was performed and those fulfilling a consensus expert opinion diagnosis of IIM were included. Clinical, serological and histological data were collected and each case was assigned a single IIM subtype. The EULAR/ACR classification criteria were then applied and sensitivity, specificity and positive and negative predictive values were calculated, presented with 95% CIs.ResultsA total of 1637 cases were screened, with 255 consensus expert opinion IIM cases ultimately identified. Applying the EULAR/ACR classification criteria, the sensitivity to diagnose an IIM was 99.6% (95% CI 97.2, 100) and 80.9% (95% CI 76.0, 85.8) for the criteria cut-points of probable and definite diagnoses, respectively. In 94/255 cases the IIM subtype differed between consensus expert opinion and classification criteria, most strikingly in the group subtyped as PM by the EULAR/ACR criteria, where there was discrepancy in the majority (i.e. in 87/161).ConclusionThe EULAR/ACR criteria performed with high sensitivity in identifying IIM in this external cohort of incident IIM. However, substantial disagreements arose between consensus expert opinion and the criteria regarding IIM subtype assignments, resulting in a large proportion of criteria-assigned cases of PM having heterogeneous features. These results may have important implications for future use of these criteria in subsequent research.

Myositis autoantibody profiles and their clinical associations in Greek patients with inflammatory myopathies.

Myositis-specific (MSAs) or-associated autoantibodies (MAAs) have been linked to particular clinical phenotypes of idiopathic inflammatory myopathies (IIM) and appear to aid diagnosis. The objective of this study was to analyze the prevalence of MSAs and MAAs and their possible clinical associations in Greek IIM patients. This study comprised 95 IIM patients classified based on the 2017 EULAR/ACR classification criteria. All patients had MSAs and MAAs measured in their sera by line immunoblot assay. Dermatomyositis was the most prevalent IIM clinical subtype. MSAs were found in 44% of the patients, whereas MAAs in 23%. The most frequently detected MSA was anti-Jo-1 (22%), while the most frequently detected MAA was anti-Ro-52 (30%). The distributions of MSAs/MAAs did not differ between the five IIM subgroups, except for anti-Mi-2 which was only detected in dermatomyositis patients. Patients with at least one MSA and/or MAA positivity showed more frequently IIM characteristic skin rashes, while those presenting solely MAA positivity had more often puffy hands and Raynaud's phenomenon. Anti-Jo1-positive patients presented more frequently lung disease, while anti-Ro52 positivity related to mechanic's hands. Anti-Ro-52 and anti-Jo-1 strongly associated with one another. Prevalence of IIM subtypes and of MSAs/MAAs in our patients is in line with published reports in populations of similar geographic distribution. While MSA and/or MAA positivity did associate with particular clinical manifestations, it did not predict in our cohort specific IIM subgroup as defined by the latest EULAR/ACR classification criteria. Future studies are warranted to conclusively decide if these autoantibodies, measured with a standardized method, should or not be incorporated in every day clinical practice to aid IIM diagnosis.

Increasing incidence of adult idiopathic inflammatory myopathies in the City of Salford, UK: a 10-year epidemiological study.

ObjectivesThe aim was to identify and characterize all incident adult cases of idiopathic inflammatory myopathies (IIM) between 1 January 2007 and 31 December 2016 in the City of Salford, UK.MethodsAdults first diagnosed with IIM within the study period were identified by: a Salford Royal NHS Foundation Trust (SRFT) inpatient episode IIM-specific ICD-10 coding search; all new patient appointments to SRFT neuromuscular outpatient clinics; and all Salford residents enrolled within the UKMYONET study. All patients with definite IIM by the 2017 EULAR/ACR classification criteria were included, as were probable cases if consensus expert opinion agreed. Cases were excluded if <18 years of age at disease onset, if they did not meet probable criteria or when probable but expert opinion concluded a non-IIM diagnosis.ResultsThe multimodal case ascertainment identified 1156 cases which, after review and application of exclusion criteria, resulted in 32 incident cases during the study period. Twenty-three of 32 were female, with a mean age of 58.1 years. The mean incidence of adult IIM was 17.6/1 000 000 person years, and higher for females than for males (25.2 vs 10.0/1 000 000 person years, respectively). A significant incidence increase over time was apparent (13.6 vs 21.4/1 000 000 person years; P = 0.032). Using EULAR/ACR classification criteria, the largest IIM subtype (21/32) was PM, followed by DM (8/32), IBM (2/32) and amyopathic DM (1/32). Expert opinion subtype differed from EULAR/ACR classification criteria in 19/32 cases.ConclusionThe incidence of adult IIM in Salford is 17.6/1 000 000 person years, higher in females, and is increasing over time. Disagreement exists between EULAR/ACR-derived and expert opinion-derived IIM subtype assignments.

Dr. Noda, et al reply.

We appreciate the comments provided by Dr. Bhansing and colleagues1 in response to our article2. Recently, Bhansing, et al showed a significant 2-fold increase in the fascia thickness of the deltoid muscles on ultrasonography (US) in patients with dermatomyositis (DM) and polymyositis (PM) relative to healthy controls3. Additionally, they showed that the deltoid fascial thickness on US in patients with DM and PM was not associated with various clinical variables, including the disease duration, serum creatine kinase, the Health Assessment Questionnaire–Disability Index score, sex, antinuclear antibody, anti-Jo1, the subtype of idiopathic inflammatory myopathy, the clinical disease … Address correspondence to Dr. K. Noda, Division of Rheumatology, Department of Internal Medicine, the Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato-ku, Tokyo, 105-8461, Japan. E-mail: knoda3353{at}jikei.ac.jp

The pathogenesis of dermatomyositis

This review looks at the many different factors thought to play a role in idiopathic inflammatory myopathies (IIM), concentrating mainly on the dermatomyositis (DM) subtype. Subject areas addressed include looking at the different clinical features of IIM, paying particular attention to the skin manifestations. There is a discussion around investigations needed with their perceived value, followed by a description of the immunohistochemical findings of DM. This review goes on to address other attributing factors such as genetic associations with the different subtypes of IIM, and environmental factors including infections, ultraviolet radiation and vitamin D deficiency and drugs. Finally, the potential immunopathogenesis of DM is summarized, looking at T cells, B cells, autoantibodies, dendritic cells, cytokines and nonimmune-mediated endoplasmic reticulum stress.

Idiopathic Inflammatory Myopathies: A Review of the Classification and Impact of Pathogenesis.

Idiopathic inflammatory myopathies (IIMs) are a group of autoimmune muscle diseases with significant morbidity and mortality. This review details and updates the pathogenesis and emerging importance of myositis-specific antibodies in the development of IIMs. An increase in the understanding of how these myositis-specific antibodies play a role in IIMs has led to the further categorization of IIMs from the traditional polymyositis versus dermatomyositis, to additional subcategories of IIMs such as necrotizing autoimmune myositis (NAM). The diagnosis of IIMs, including manual muscle testing, laboratory studies, and non-invasive imaging have become important in classifying IIM subtypes and for identifying disease severity. Treatment has evolved from an era where glucocorticoid therapy was the only option to a time now that includes traditional steroid-sparing agents along with immunoglobulin therapy and biologics, such as rituximab.

The role of magnetic resonance imaging techniques in evaluation and management of the idiopathic inflammatory myopathies.

Magnetic resonance imaging (MRI) is an important tool in the evaluation of neuromuscular disorders. MRI accurately demonstrates muscle oedema, atrophy, subcutaneous pathology and fatty infiltration and also highlights the distribution of muscle involvement. This review examines the role of MRI in evaluation of the idiopathic inflammatory myopathies (IIMs), a heterogeneous group of autoimmune conditions characterised by muscle inflammation and a variety of extra-muscular manifestations. MRI has a clear role in aiding diagnosis of these conditions, guiding muscle biopsy, differentiating subtypes of IIM using a pattern-based approach, and monitoring disease activity in a longitudinal fashion. Whole body MRI is an emerging technique that offers several advantages over regional MRI, but is not currently widely available. We will also consider newer MRI techniques which provide detailed information regarding the metabolism, function and structure of muscle, although their use is restricted to research purposes at present.

A Case of New-Onset Dermatomyositis in the Second Trimester of Pregnancy: A Case Report and Review of the Literature.

Dermatomyositis (DM), a subtype of idiopathic inflammatory myopathies (IIMs), is characterized by skin rash, proximal muscle weakness, and inflammatory infiltrates in the muscle tissue. The peak incidence of the disease is at the age of 50–60 years, and only 14% of the patients with IIMs are estimated to present during reproductive years. Because of the limited pregnancy experience in patients with IIMs, little is known regarding the effects of DM on pregnancy or vice versa. We herein report a 40-year-old woman who developed DM in the second trimester of her pregnancy and did not respond to treatment with methylprednisolone. Her pregnancy was terminated at the 32nd week of gestation, due to preeclampsia and fetal distress. She delivered a healthy baby and improved rapidly after delivery. We have searched PubMed for relevant articles and reviewed previously published cases.

Immune-Mediated Necrotizing Myopathy: Update on Diagnosis and Management.

The idiopathic inflammatory myopathies (IIMs) comprise a group of autoimmune disorders that target skeletal muscle. They are characterized by typical laboratory and clinical features including muscle weakness, elevated muscle enzymes, characteristic histopathology of muscle biopsies, as well as electromyography abnormalities. The IIMs are divided into polymyositis, dermatomyositis, inclusion body myositis, nonspecific myositis, and immune-mediated necrotizing myopathy (IMNM). IMNM is distinguished by the absence of primary inflammation on muscle biopsy. IMNM may be associated with myositis-specific autoantibodies (i.e., anti-SRP and anti-HMGCR) and malignancy, in association with viral infections (HIV or hepatitis C), or in relation to other connective tissue diseases (i.e., scleroderma). Typical clinical findings such as severe muscle weakness, highly elevated creatine kinase (CK) levels, as well as resistance to conventional immunosuppressive therapy are associated with this subtype of IIM. This review provides an overview of this disease entity and focuses on its diagnosis and treatment.

Role of MRI in diagnosis and management of idiopathic inflammatory myopathies.

The idiopathic inflammatory myopathies (IIM) represent a heterogeneous group of muscle diseases. Given their potential amenability to immunosuppressive treatment, the early diagnosis of the IIM subtype and the exclusion of "myositis mimics" are of great importance. MRI can visualize muscle edema, fatty replacement, atrophy, subcutaneous pathology, and fasciitis. MRI furthermore provides information about the distribution of muscle involvement and help in guiding of muscle biopsy. This review discusses significant MRI developments aimed at improving the diagnostic sensitivity and specificity, and at assessing IIM activity and damage. The manuscript also highlights techniques such as magnetic resonance spectroscopy, blood oxygenation level-dependent MRI, and diffusion-weighted MRI and T2 mapping which may in the future allow to better characterize vascular involvement, metabolic reserves, dynamic muscle recruitment, and treatment outcome.

Diagnosis, pathogenesis and treatment of myositis: recent advances

Dermatomyositis (DM), polymyositis (PM), necrotizing myopathy (NM) and inclusion body myositis (IBM) are four distinct subtypes of idiopathic inflammatory myopathies - in short myositis. Recent studies have shed some light on the unique pathogenesis of each entity. Some of the clinical features are distinct, but muscle biopsy is indispensable for making a reliable diagnosis. The use of magnetic resonance imaging of skeletal muscles and detection of myositis-specific autoantibodies have become useful additions to our diagnostic repertoire. Only few controlled trials are available to substantiate current treatment approaches for myositis and hopes are high that novel modalities will become available within the next few years. In this review we provide an up-to-date overview of the pathogenesis and diagnostic approach of myositis. We aim to present a guide towards therapeutic and general management.

P.21.8 Long-term follow up of a cohort of 62 newly diagnosed patients with a subacute-onset idiopathic inflammatory myopathy

Long-term outcome of subacute-onset idiopathic inflammatory myopathies (IIM) varies widely. Available data comes mostly from retrospective studies. We present the follow up results of a large prospective cohort of 62 patients with subacute-onset IIM (dermatomyositis (DM, n = 24), nonspecific myositis (NSM, n = 34), necrotizing autoimmune myositis (NAM, n = 4)) after first line treatment with corticosteroids (Dexa myositis Trial). Development of concomitant autoimmune disease or malignancy, disease course and mortality, functional outcome and quality of life were evaluated. After a median follow up of 3.1 years (0.1–5.9) 22% had developed a concomitant connective tissue disease (CTD) and 17% a malignancy (CTD most frequent in NMS and cancer in DM). The mean time between diagnosis and malignancy was 22 months. Disease related mortality of the study cohort was 15%. A monocyclic disease course was found in 34% of which 20% had tapered all medication. Most patients (66%) had a chronic disease course and experienced single or multiple relapses requiring different modalities of immunosuppressive treatment. Disability scores as measured by the Rankin score and the Neuromuscular Symptom Score improved in the fist 18 months. At follow up 68% still perceived disabilities. Quality of life scores as measured by the SF36 improved in the first 18 months as did disability scores. After 18 months, scores remained stable during the next years of follow up and remained low compared to the normal population, even in patients without signs of active disease. 1. Two-thirds of the patients develop a polycyclic disease course and need maintenance treatment. 2. The impact on functional outcome and quality of life is considerable. 3. Repeated malignancy screening is needed in all IIM subtypes, on an annual basis for at least two years after diagnosis. 4. It is of utmost important to inform subacute-onset IIM patients about prognosis.

P.21.1 Autophagy as a link between immunity and inflammation in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of immune-mediated muscle disorders characterized by muscle inflammation and weakness. They comprise inclusion body myositis (IBM), polymyositis (PM), juvenile dermatomyositis (JDM) and adult dermatomyositis (DM). Autophagic pathway impairment has been well documented in sporadic IBM, where it has been suggested to be responsible for the accumulation of multiple-protein aggregates, typical of the myopathy. The main candidates responsible for this impairment are suggested to be TLRs. We evaluated the autophagic process also in PM and DM, in particular the interaction between autophagosome maturation and innate immune system. LC3 and other autophagic molecules, together with TLR3, TLR4, HSP60 and HMGB1/2 were analyzed in IIM and control muscles by qPCR, immunohistochemistry and immunoblot. Myoblasts and myotubes from PM, DM and control muscle biopsies were analyzed to evaluate changes in TLR and HMGB1/2 expression after induction or inhibition of autophagy. Gene expression analysis showed a dysregulation of autophagy in all IIM subgroups. A tight correlation between autophagy and innate immunity in myopathic muscles compared to controls was highlighted by confocal microscopy; activation of stress response and the presence of bacterial infection were observed connected with an abnormal accumulation of autophagosomes in IIM myofibers. These findings demonstrate the involvement of the autophagic process in the pathogenesis of all subtypes of IIMs; it is not clear if this mechanism represents a consequence or a cause of the induction of immune response and inflammation. Autophagic machinery components might represent a possible target for new therapeutic approaches for IIM.

Immunoregulation in Idiopathic Inflammatory Myopathies: From Dendritic Cells to Immature Regenerating Muscle Cells

Idiopathic inflammatory myopathies (IIM) are a group of chronic muscle disorders of unknown origin that lead to muscle destruction. The original classification of IIM proposed by Bohan and Peter in 1975 including polymyositis (PM) and dermatomyositis (DM) was recently revised with the development of histopathological approaches and the discovery of myositis-specific and myositis-associated antibodies that led to the characterization of new entities. In addition to PM and adult and juvenile DM, these novel classifications distinguish inclusion-body myositis (IBM), immune-mediated necrotizing myopathy, overlap myositis, and cancer-associated myositis1,2. While distinct immunopathogenic mechanisms may occur in each subset of myositis, all IIM share a common inflammatory background associated with clinical, histological, and serological overlap. Several molecular pathways, such as adaptive and innate immune responses, autoimmunity, and nonimmune mechanisms, could influence the pathogenesis of IIM. However, the exact contribution of each one in the development of distinct phenotypes remains unclear. In this issue of The Journal , Gendek-Kubiak and Gendek highlight the contribution of dendritic cells (DC)3. We summarize here recent insights in myositis immunoregulation from DC that are central in the development of adaptive and innate response to nonimmune mechanisms. ### Dendritic cells DC are crucial for the development of adaptive and innate immune responses. DC, subdivided into myeloid DC (mDC) and plasmacytoid DC (pDC), are present in lymphatic and blood systems and peripheral organs. They are equipped with a range of pattern-recognition receptors (PRR) and serve as sentinels of the immune system. Their activation after stimulation of PRR, such as Toll-like receptors (TLR) or C-type lectin receptors (CLR), by microbial components and/or endogenous ligands leads to their maturation and the development of an effector T cell immune response. In muscle biopsies from IIM, both myeloid and plasmacytoid DC have been detected with differences according to IIM subtypes. The DC … Address correspondence to Dr. A. Tournadre, Department of Rheumatology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, 58 rue Montalembert BP69, 63003 Clermont-Ferrand Cedex 1, France. E-mail: atournadre{at}chu-clermontferrand.fr

Toll-Like Receptors Promote Inflammation in Idiopathic Inflammatory Myopathies

The roles of Toll-like receptors (TLRs) and their myeloid differentiation response gene 88 (MyD88)-dependent and MyD88-independent signaling cascade particularly with regard to the pathogenesis and regulation of immune responses in idiopathic inflammatory myopathies are unclear. We investigated these pathways in muscle biopsies from 5 cases each of polymyositis, inclusion body myositis, dermatomyositis, vasculitis-associated interstitial myositis, and noninflammatory neurogenic atrophy. Toll-like receptor 2, TLR4, TLR9, and MyD88 mRNA transcripts and protein expression were increased in all subtypes of idiopathic inflammatory myopathies. Upregulation of MyD88 was associated with increased mRNA levels of interferon-γ, interleukin 12p40, and interleukin 17, suggesting NF-κB activation via the MyD88-dependent pathway in early stages. The costimulatory molecules CD80 and CD86 were expressed on inflammatory infiltrates in idiopathic inflammatory myopathies and may additionally contribute to activation of the MyD88-independent pathway, leading to nuclear factor-κB activation in late stages. Our data suggest that nuclear factor-κB activation via both the MyD88-dependent and the MyD88-independent pathways contributes to the proinflammatory milieu in idiopathic inflammatory myopathies.

Distribution of the NF‐κB Complex in the Inflammatory Exudates Characterizing the Idiopathic Inflammatory Myopathies

The transcription factor nuclear factor-kappaB (NF-kappaB) is a ubiquitously expressed protein family that is considered crucial in autoimmunity. We describe NF-kappaB p50 and p65, and the inhibitor I-kappaB alpha in the inflammatory exudates characteristic for the different idiopathic inflammatory myopathies (IIM), that is, endomysial CD8(+) cytotoxic T cells invading non-necrotic fibers in polymyositis (PM) and sporadic inclusion body myositis (sIBM), and the perimysial/perivascular CD20(+) B cells and CD4(+) T cells in dermatomyositis (DM). We also analyzed other inflammatory cells in the vicinity of active inflammation sites. Strikingly, actively invading CD4(+) cells in PM and sIBM contained both p65 and p50, whereas I-kappaB alpha was absent. This could point to a high activation state in which these cells are capable of expressing a variety of inflammatory mediators, contributing to the degradation of non-necrotic fibers. Secondly, CD68(+) macrophages in the infiltrates in all three IIM subtypes showed strong nuclear p50 and I-kappaB alpha staining. This may point to a role for p50 in counteracting inflammation, a reaction that could be enhanced by an upregulation of I-kappaB alpha as we observed with immunofluorescence. These results shed further light on the immunopathology of PM, sIBM and DM. CD4(+) and CD68(+) mononuclear cells may play a more prominent role than previously assumed.